Sigmoidoscopy looks at the lower one-fourth of the colon (rectum, sigmoid). It is useful when your physician wants to confirm the presence of inflammation or a source of bleeding (such as hemorrhoids) within the reach of the scope. Sigmoidoscopy helps rule out infectious causes of inflammation, such as disease caused by germs which may mimic IBD. It is also useful in evaluating symptoms that do not respond to your current treatment or that return despite medications. In these cases, your doctor can use the sigmoidoscope to take biopsies from any abnormal areas. This will allow him or her to confirm the diagnosis and assist in excluding treatable infections that can trigger an IBD flare-up.
A colonoscopy can assess the complete extent and severity of colitis. This is important for determining the type of therapy needed. It is also essential to evaluate as well as take biopsies of the very end of the small intestine (terminal ileum). This last segment of the small bowel and the beginning of the colon are most often the areas affected by Crohn’s disease (Figure 1). Chronic inflammation of the colon (colitis) is known to increase the risk of colon cancer. Years of poorly controlled colonic inflammation is thought to lead to abnormalities in certain genes in the cells forming the lining the colon (called dysplasia). Since dysplasia can only be seen under the microscope, colonoscopy is needed to obtain multiple biopsies throughout the entire colon and rectum to screen for this pre-cancerous condition. The time to start performing colonoscopy for surveillance depends on how long the patient has had colitis, and the extent of colon involved with the colitis. Surveillance refers to routine examinations of the colon to minimize the risk of cancer by checking for dysplasia and monitoring any changes, usually starting about 8 years after onset of colitis.
EGD and Enteroscopy
EGD is a common procedure that is used to evaluate a wide variety of symptoms, such as abdominal pain, nausea, vomiting, and painful swallowing. Unlike ulcerative colitis, Crohn’s disease can affect the esophagus, stomach, and small bowel. Biopsies of these “upper” parts of the gastrointestinal tract can be very helpful to demonstrate that a patient does have Crohn’s disease, rather than ulcerative colitis. Unfortunately, about 15 feet (5 meters) of small bowel are beyond the reach of an EGD. Occasionally a longer EGD, called an enteroscope, may be used to examine further in the small intestine to evaluate these symptoms. Even with an enteroscope, more than one-third of the small bowel cannot be reached. If small bowel Crohn’s is suspected, your doctor will recommend radiological tests, such as small bowel X-rays and other CT or magnetic imaging scans to determine whether there is disease in the small intestine. A very new technique, called balloon endoscopy (Figure 9) employs one or two balloons to reach all segments of the small bowel.
Wireless Capsule Endoscopy
Capsule endoscopy has justifiably received a lot of publicity recently. It has permitted the visualization of the entire small bowel using a non-invasive swallowable “pill” camera. This test has been proven to be the best to demonstrate the presence of lesions typical of small bowel Crohn’s disease in segments that are too far to reach with any endoscopie except possibly the double balloon scope. The key to the preparation for this test consists of a liquid diet the day prior to the exam and fasting after the evening meal. The morning of the test, the patient is fitted with a belt that contains a recorder (Figure 7). The patient then swallows the endoscopy capsule, which is the size of a large jellybean or vitamin tablet. While the patient goes about their regular activities, the capsule travels down the small intestine and transmits approximately 50,000 images to the recording device. After 8-10 hours, the recorder is returned to have the images downloaded to a special computer station. The doctor can then review the images. The capsule itself is disposable; the capsule is excreted in the stool effortlessly. For patients with known Crohn’s disease, there is a risk that the capsule can get stuck behind a narrowing or “stricture” of the small bowel. Therefore, it is safest to determine that there are no strictures or scarred, narrowed bowel segments before the capsule camera can be used. This is done using a “dummy” dissolvable capsule which is the same size as the real “pill” camera.
Endoscopic retrograde cholangiopancreatography (ERCP)
In a small percentage of patients with IBD, serious liver disease can occur. The most common type is called “primary sclerosing cholangitis” (PSC). A doctor may suspect PSC if blood tests results repeatedly reflect abnormal elevations of liver enzymes. An ERCP is usually performed to help confirm the diagnosis. ERCP is a method that combines X-rays and endoscopy to examine the bile ducts and pancreatic ducts. As in an EGD, a tube is passed through the stomach and into the beginning of the small bowel (duodenum). The papilla, a small bump with a tiny opening is located in the duodenum (small bowel immediately after the stomach) (Figure 11). This papilla is the exit valve for the biliary and pancreatic ducts. A small catheter is introduced through the papilla into either your bile ducts or your pancreatic duct and contrast dye is injected. X-rays then demonstrate the structure of these ducts outlined by the contrast dye. This test allows the doctor to look for disease in the ducts, such as gallstones or narrowing due to PSC. It also allows the physician to open up ducts that are blocked or to remove gallstones.
Endoscopic ultrasound (EUS)
Endoscopic ultrasound (EUS) is another relatively new technique that uses an ultrasound probe attached to an endoscope to obtain deep images of the internal organs such as the pancreas. In IBD, this is most often used to look at fistulas in the rectal area. Fistulas occur as a complication of Crohn’s disease but are not seen in ulcerative colitis. They consist of abnormal channels or canals from one segment of the intestine to another part of the intestine or to another organ of the body (such as the skin near the buttocks, or the vagina). EUS can determine the depth and extent of the fistula (Figure 13) and biopsies can be taken if needed.